Small-sized drill and method for producing same



Jan. 17, 1961 LATOUR 2,968,200

SMALL-SIZED DRILL AND METHOD FOR PRODUCING SAME Filed 001;. 2, 1957 g m'l'o f Hen r] W ,j. gamvw 4 Horwy United tes Patent SMALL-SIZED DRILL AND METHOD FOR PRODUCING SAME Henri Latour, Geneva, Switzerland, assignor to Marie- Loulse Klein, Geneva, Switzerland Filed Oct. 2, 1957, Ser. No. 687,652 Claims priority, application Switzerland Oct. 4, 1956 2 Claims. (Cl. 77-67) The present invention has for its object a small sized drilling or boring tool including a body or socket made of moldable material cast over a wire arranged axially of the socket and of which one end serving for drilling purposes projects beyond one end of said socket.

The invention covers also a method for producing such a tool, said method consisting in casting a moldable material over a wire so as to form a socket beyond one end of which the end of the wire which is to serve for boring purposes projects.

The accompanying drawings illustrate by way of example three embodiments of the object of the present invention together with the method for producing two of said embodiments. In said drawings:

Fig. 1 is an axial cross-section of the first embodiment -and Fig. 2 is an end view thereof as seen from the left hand side of Fig. 1.

Figs. 3 and 4 are axial cross-sections of the second and third embodiments respectively.

Fig. 5 is a diagrammatic plan view of a half shell used for molding the tool illustrated in Fig. 3 and Fig. 6 is a perspective view of a section of said half shell.

Fig. 7 is an axial sectional view of an arrangement for molding the embodiment illustrated in Fig. 4.

The tool illustrated in Figs. 1, 2, 3, and 4 includes a body or socket 1 of a material adapted to be molded at a comparatively low temperature such as tin, lead or a thermoplastic material, for instance a polyamide of the type sold under the registered trade name nylon. It is also possible to resort to a synthetic glue adapted to harden at room temperature in the presence of a hardening agent such as that sold under the registered trade name Araldite. This socket is cast over a wire 2 such as a steel wire arranged axially of the socket and of which one end serves for drilling or boring purposes and projects beyond the left hand side of the socket. Said socket is provided at its other end with a frusto-conical extension 3 3 (Figs. 1 and 3) which allows driving it into a recess formed at the end of the toolholder spindle of the drilling machine or else if this extension is formed with a frustoconical recess 3, forming a small chamber C near its front end, it may be fitted over the correspondingly shaped end 14 of said spindle. Said small chamber C is between the front end of the spindle and the front end of said recess (Fig. 4).

The tool illustrated in Fig. 3 may be executed through molding inside two similar superposed cooperating shells of which one, subdivided into two sections 4 and 5, is illustrated in plan view in Fig. 5, the section 4 being also illustrated in perspective view in Fig. 6. Each shell includes a series of elementary half-molds 7 and each of the latter opens at one end into a first groove 6 aligned with the axis of symmetry of the half-mold. A second groove 9 is formed also in alignment with the axis of symmetry of each half-mold in an inner expansion 10 formed inside the half-mold while a pipe 11 serves for injecting the moldable material into the other end of each half-mold in alignment with the axis of symmetry of the latter. 6

A wire 2 is set in the aligned grooves 6 and 9 of each hold-mold and after the cooperating shell has been superposed, the moldable material is injected through a pipe 11 into each half-mold. The pressure producedby injection leads often to a lateral shifting of the end 12 (Fig. 3) of the wire 2 which is embedded in the mass of each socket but, since the other end is held in the aligned grooves 6 and 9, the free end of the wire 2 which is to execute the drilling remains set along the axis of the socket 1 after the tool has been lifted.

The tool illustrated in Fig. 4 may be obtained by casting in a mold including two shell members 15 and 16 (Fig. 7) arranged in coaxial relationship. The shell member 15 is provided with an axial opening 17 and the shell member 16 carries pincers 18 adapted to slide coaxially inside the shell member 16 and to open when it moves forwardly against the pressure of the spring 19 upon actuation of the control knob 22. A block 20 provided with an axial bore 21 is also fitted so as to slide along the axis of the shell member 16 and to engage the head of the pincers 18, which arrangement allows the socket 1 to be ejected out of the shell member 16 at the moment of the lifting when the pincers 18 are urged forwardly against the pressure of the spring 19.

For the casting of a tool, the wire 2 is inserted inside the mold through the opening 17 in the shell 15, the pincers being in their open forward position, this being done after the shell members 15 and 16 have been brought into engagement. The moldable material is then injected into the mold through the lateral pipes 11 and, when the material has set hard, the shells 15 and 16 are disengaged. The socket 1 obtained through molding is finally ejected as provided by exerting a thrust on the knob 22 rigid with the outer end of the pincers 18 against the pressure of the spring 19. When the shell members 15 and 16 are reengaged, the mold is again ready for a further casting operation.

Hitherto, small drilling tools were fitted by hand in the tool-holder spindle of the boring machine and they were secured inside the axial recess of the cooperating spindle by means of shellac which was made liquid at the moment of the fitting and allowed to harden thenafter. This difficult operation requires a skilled workmanship and did not always lead to favorable results since it is a diflicult matter to position the wire 2 exactly along the axis of the spindle. These drawbacks cannot be found in the embodiments illustrated; the wire 2 lies always accurately along the axis of the socket and it is possible to obtain a large number of tools through a single casting operation.

What I claim is:

l. A small boring tool adapted to be fitted over the end of a machine-tool spindle, comprising a body of revolution of synthetic plastic material, the rear end of which matches said end of the machine-tool spindle, said body being provided with an inner recess forming a small chamber near its front end, and a short wire element, the length of which is a small multiple of the diameter of said body of revolution, embedded inside said body of revolution coaxially therewith, extending through the chamber formed in the latter and projecting axially by a small extent beyond the front end of said body.

2. A small boring tool adapted to be fitted over the end of a machine-tool spindle, comprising a body of revolution of synthetic plastic material, the rear end of which is provided with a recess adapted to be engaged by the machine-tool spindle, said recess extending into a small chamber to the front of the location of the machine-tool spindle, and a short wire element, the length of which is a small multiple of the diameter of said body of revolution, embedded inside said body of revolution coaxially therewith, extending rearwardly into the chamber formed References Cited in the file of this patent UNITED STATES PATENTS 361,452 Sawyer Apr. 19, 1887 4 Mazzoni Mar. 14, 1950 'Doepker Mar. 4, 1952 Graves June 2, 1953 Auldridge June 30, 1953 Schleich Dec. 13, 1955 Pay Sept. 18, 1956 FOREIGN PATENTS Italy July 5, 1927 

